Method of producing non-woven fabric



Sept. 27, 1966 K. SPONSEL METHOD OF PRODUCING NON-WOVEN FABRIC Filed Sept. 28, 1964 INVENTOR.

KURT SPONSEL United States Patent METHOD OF PRODUCING NON-WOVEN FABRIC Kurt Spouse], Mallerstrasse 51, Dusseldorf- Nord, Germany Filed Sept. 28, 1964, Ser. No. 399,660 Claims priority, application Germany, Oct. 2, 1963,

7 Claims. 01162-101 Thehigh speed production of non-woven fabrics of natural or synthetic fibers has given great problems for a long-time. N. Bigler explained the basic reasons for the difficulties of high speed. production in the special issue of the Swiss trade journal for textile improvements (see Non-woven Fabrics SVF 17th year, numbers 6 and 7 of- June and July, 1962) and has indicated production speeds of 400 meters/min. are desired.

Existing equipment for the manufacture of webs are running at speeds of D8 to 40 meters/min. with a Web width of 2 meters and are basically retarded in speed by the use of carding machines to open the fiber clusters and form -a dry fiber web.

Fiber-opening equipment developed in the United States, like the Rando Web'ber, the Callaghan Machine, etc., up till now have the disadvantage that the fiber is non-uniform with. respect to the weight per square meter.

While forming a Web involves a three dimensional process, at the same time it is necessary that chemical and technical means Work together to be able to form a web on conventional paper machines running at production speeds of 400 meters/min. For this reason, it is no surprise that many methods of Web forming are in full development, as evidenced by numerous machine and process patents.

The process of the present invention is similiar to the method of manufacturing fiber leather in which the quilted leather waste is mixed with a binding material emulsion and by adding precipitating material, water removal is accomplished and a bonding of the leather fibers with the dispersed bonding material is achieved.

It is well known that on conventional paper machines, it is only possible to make papers from fiber material comprising short fibers, up to 12 millimeters in length. However, the modern non-woven webs are formed of fibers of 60 or even 80 millimeter length and one cannot make use of the standard methods of preparation in the pulper, hollauder or chopper and a new approach must be taken. This consists of the following:

When cationically charged fibers are dusted on a foam made of an anionic binder like a polyvinylacetate emulsion, then the emulsion will break down and the binder material precipitates onto and combines With the cationic fibers and the water may thereafter be removed. The speed of the process can be increased by the addition of other cationic means for accelerating the precipitation or by adding flocking'agents, such as aluminum sulfate.

Specifically, in this process, cationically charged fibers, such .as polyester fibers or cellulose acetate fibers coated with fattyalkylpropylene di-amine acetate, may be uniformly dispersed on a butadiene-sty-rene dispersion foam. The butadiene-styrene dispersion breaks down or flocculates, depositing the but-adiene-styrene binder material onto the fibers and enabling the water from the dispersion to be removed, all of which may be performed at high production speeds. Long experiments suggest that uniform deposition of the fibers into a web can best be accomplished by pneumatically conveying the fibers to a layer of pre-laid binder foam utilizing rotating screens to obtain a uniform distribution of fibers across the web. This method of delivering fibers to the foam belongs to 3,275,496 Patented Sept. 27, 1966 this new principle of high speed production of nonwoven webs. It is also contemplated that the treated,

cat-ionically charged'fiber, can be dispersed in the binder foam before the foam is laid out in a web.

Other objectives, advantages and features of the invention will be apparent from the following detailed description of preferred embodiments of the invention wherein reference is made to the accompanying drawing forming a part hereof and wherein:

FIG. 1 is a schematic elevational view of apparatus for practicing the method of this invention; and,

FIG. 2 is a schematic illustration of a modification of the apparatus of FIG. 1.

The apparatus illustrated in FIG. 1 is similar to appara-tus which has been employed to practice this invention in the production of non-woven fabric having a weight of 27 grams/square meter and a width of 20 centimeters at a speed of 200 meters per minute, An emulsion mixture of latex adhesive is formed by the introduction into a vat 11 of 8 'liters of water and a foamable adhesive compound consisting of grams of polyvinylacetate as an adhesive agent, 40 grams of methyl cellulose .as a suspending, or emulsifying, agent and 40- grams of a suitable plasticizer. This foamable emulsion, indicated at 12 is subjected to violent agitation by means of a 'high speed impeller '13 and high pressure lair introduced through the bottom of vat 1 1 through a pipe 14.

A multiplicity of synthetic fibers have been previously treated to render them cationically charged and are stored in a hopper 16. By way of example, a suitable treatment may involve 800 grams of viscose rayon of. 1.2 denier having a fiber length of 60 millimeters. These fibers are rendered cationic by coating them with a cationic organic amine in the form of 32 grams fattyalkylpropylene diamine acetate. The fibers may additionally be treated with 40 grams of aluminum sulfate as .a coagulating, or precipitating, agent for the adhesive emulsion in the binder foam.

Foam produced in vat 11 is fed through a slice 17 onto a moving foraminous wire 18 driven at a speed of 200 meters per minute and supported at the ends of its loop by rolls 19. Foam binder is deposited on wire 18 at a rate sufficient to form a foam web 20 across the wire to a depth of 1 centimeter.

The previously treated, cationically charged fibers, indicated at 21 are fed from hopper 16 through a grinding and sieving unit 22 and into a separator 23 from which the fibers are dispersed onto the binder foam web 20. Upon contacting the foam the cationic fibers and the coagulating agent thereon act to break down the adhesive emulsion in the foam allowing the polyvinylacetate adhesive to adhere to and bond together fibers in the foam.

Wire 18 with the foam web 20 and fibers 21 thereon pass over a series of suction boxes 24 which effect removal of water released from the emulsion and excess foam material leaving a coherent web of bonded fibers on the wire. The non-woven Web thus formed may thereafter he removed from the wire by means of a felt or a :felt covered roll 26 and transferred to the surface of a large drying drum 27 which drives the remaining water from the web. The dry web is removed from the drying drum with the aid of a scraper, or doctor blade 28 and the finished web 29 may thereafter be rolled up on a reel (not shown).

The process of this invention may be practiced in a modified form on the apparatus illustrated schematically in FIG. 2. In this embodiment the adhesive foam emulsion 12, prepared as stated above, is introduced into a vat 31 having an impeller 13 and a compressed air pipe mass of binder foam. To this mass are introduced the charged fibers 21, prepared as stated above; The mixture of fibers 211and foamed adhesive emulsion 12 are conveyed to the moving wire '18 through a slice 32 communicating with vat 31 and having oppositely rotating cylindrical screens or sieves 33 disposed therein for breaking up and dispersing the charged fibers within the foam. The web 34 of fibers and binder foam deposited on wire 18 is thereafter dewatered and dried as described in con. nection with FIG. 1.

What I claim is: V v

1. The method of producing a non-woven fabric which comprises treating fibers to render them cationically charged, dispersing the charged fibers onto a layer of an anionically charged aqueous synthetic bonding material foam, removing water from the resulting mixture of fibers and foam and drying the bonded fibers. g

2. The method of producing a non-woven fabric'which comprises preparing a foam layer from an emulsion of anionically charged synthetic bonding material, deposit-' ing onto a multiplicity of synthetic fibers a cationic substance-and a coagulating agent, dispersing the fibers thus.

treated onto the foam layer, said coagulating agent being effective to break the emulsion of bonding material and enable the bonding material to adhere to said fibers, with.- drawing foam and water. from said fibers and thereafter drying the bonded fibers.

3. The method of producing a non-woven fabricwhich comprises preparing a foam layer of anionically charged synthetic bonding emulsion, introducing into said foam.

fibers having cationic organic amine material thereon, introducing to said foam a precipitating material to .break down the bonding emulsion, removing water and foam from the fibers and thereafter. drying the bonded web of fibers thus formed.

4. The method of producing a non-woven fabric which comprises treating fibers to render them 'cationicafl 'ly charged, depositing onto a forarninous member a web of anionically charged aqueous synthetic bonding; material foam, dispersing the treated fibers onto the web of foam, removing water from the resulting mixture through the forarninous member and thereafter drying the resulting bonded web of fibers.

5. The method of producing a non-woven fabric whic comprises preparing a foammass from an emulsion of anionically charged synthetic bonding material; depositing onto a multiplicity of synthetic fibers a cationic substance and a coagulating agent, conveying the bonding I material foam and the treated fibers to a foraminous member and spreading them in a layer thereupon, said. coagulating agent being effective to break down the bonding material emulsion when contacted therewith, remov ing water and foam through the foraminous member and thereafter drying the resulting bonded web of fibers.

6. The method of producing a non-woven fabricwhich comprises treating fibers to :render them cationically charged, dispersing the charged fibers into-an anionically charged aqueous synthetic bonding material foam, forming said foam carrying said dispersed charged .fibersinto a layer, removing Water from the resulting mixture, of fibers and foamand drying the bonded fibers;

7 The method of producing a non-woven fabric which comprises preparinga foam mass from anemulsion of anionically charged synthetic bonding material, depositing onto a multiplicity of synthetic fibers a cationic substanceand a coagulating agent, conveying the bonding material foam to a foraminous member and spreading it in a layer thereupon, dispersing the treated fibers upon said layer of foam, said coagulating agent being effective to break down the bonding material emulsion when contacted therewith, removing water and foam through the foraminous member and thereafter, drying the resulting bondedrweb DQNALL H. SYLVESTER, Primary Examiner.

I. H. NEWSOME, Assistant Examiner, 

1. THE METHOD OF PRODUCING A NON-WOVEN FABRIC WHICH COMPRISES TREATING FIBERS TO RENDER THEM CATIONICALLY CHARGED, DISPERSING THE CHARGED FIBERS ONTO A LAYER OF AN ANIONICALLY CHARGED AQUEOUS SYNTHETIC BONDING MATERIAL FOAM, REMOVING WATER FROM THE RESULTING MIXTURE OF FIBERS AND FOAM AND DRYING THE BONDED FIBERS. 